Carbon Dioxide (R744/CO2) as as Refrigerant Code of Practice

The publication provides essential industry guidance for owners, designers, installers and operators of vapour compression refrigerating systems that use carbon dioxide as a refrigerant. It covers properties of refrigerants, decommissioning, testing and maintenance as well as design issues with useful appendices such as typical schedules for inspection and maintenance, system register details, machinery rooms, definitions and an updated list of relevant standards.  The Code has been prepared by the IOR Technical Committee as a reference source and guide to interpretation of current safety standards such as BS EN378:2016 and legal requirements such as PED, PSSR and PUWER.  

The IOR publishes four Safety Codes of Practice specific to refrigerant type.  

• Non Flammable, Lower Toxicity Refrigerants Group A1 (under revision)
• Flammable Lower Toxicity Refrigerants Group A2L, A2 and A3 (reissued April 2018)
• Carbon Dioxide R744 (under revision)
• Ammonia R717 (reissued May 2018)

This Code is supplied as a 93 page PDF

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Full Contents list

Section 1 – Scope and Limitations            

Section 2 – Relevant Properties of Carbon Dioxide          

2.1 Carbon Dioxide         

2.2 Potential Hazards     

Section 3 – Design of Components          

3.1 General        

3.2 Component Design and Test Pressures          

3.3 Compressors             

3.3.1 General    

3.3.2 Design Criteria       

3.3.3 Pressure Testing   

3.3.4 Nameplate Data   

3.4 Pressure Vessels and Heat Exchangers          

3.4.1 General    

3.4.2 Design Pressures  

3.4.3 Test Pressures       

3.4.4 Nameplate Data   

3.4.5 Pressure Vessels  

3.4.6 Shell and Tube Heat Exchangers    

3.4.7 Coil or Grid Exchangers      

3.4.8 Plate and Plate & Shell Heat Exchangers    

3.5 Liquid Refrigerant Pumps     

3.5.1 Design Criteria       

3.5.2 Test Pressures       

3.5.3 Nameplate Data   

3.6 Refrigerant Control Valves and Sensing Devices         

3.6.1 General    

3.6.2. Design Pressure and Temperature              

3.6.3. Manufacturing Tests         

3.6.4 Nameplate Data   

3.6.5 Shut-Off Valves    

3.6.6 Liquid level indication         

Section 4 – System Design and Installation

4.1 General        

4.2 Material Selection   

4.3 Steel Piping Systems              

4.3.1 Pipe Materials       

4.3.2 Pipe Connections 

4.3.3 Pipe Supports and Hangers              

4.4 Copper Piping            

4.4.1 Pipe Connections 

4.4.2 Pipe Supports and Hangers              

4.5 Location and Arrangement of Piping

4.6 Arrangement of Isolating Valves       

4.7 Instrumentation       

4.7.1 General    

4.7.2 Arrangement of Pressure Indicators            

4.7.3 Liquid Level Indicators        

4.7.4 Liquid Level Glasses            

4.8 Protection against Excess Pressure  

4.9 Protection against Environmental Effects      

4.10 Notification to Local Authorities      

4.11 Refrigerant Detection          

4.12 System Labelling    

4.13  Allowable Refrigerant Charge         

Section 5 – System Testing         

5.1 General        

5.2 Strength Test Procedure      

5.3 Tightness Test Procedure     

5.4 Test Certificates       

Section 6 – Commissioning of New Installations

6.1 General        

6.2 Evacuation and Dehydration               

6.3 Charging      

6.4 Protection Devices  

Section 7 - Inspection and Maintenance               

7.1 General        

7.2 System Log 

7.3 Routine Inspection  

7.3.1 General    

7.3.2 Logging System Performance         

7.3.3 Pipework 

7.3.4 Compressors          

7.3.5 Condensers and Evaporators          

7.3.6 Liquid Pumps         

7.3.7 Pressure Relief Devices and Pressure Controls       

7.4 Major Inspection     

7.4.1 System     

7.4.2 Pipework

7.4.3 Compressors          

7.4.4 Pressure Vessels and Heat Exchangers       

7.4.5 Refrigerant Pumps              

7.4.6 Stop Valves, Safety Valves and Control Devices      

7.5 Pressure System Examination            

7.5.1 General    

7.5.2 Uninsulated Vessels and Heat Exchangers

7.5.3 Insulated Vessels and Heat Exchangers      

7.5.4 Extended Surface Heat Exchangers and Grid Coils 

7.5.5 Plate Heat Exchangers       

7.5.6 Piping        

7.5.7 Pressure Test for Strength               

7.5.8 Extent of Tightness Test    

Section 8 - Documentation         

8.1 General        

8.2 Risk Assessment      

8.3 Health and Safety File            

8.4 Written Scheme of Examination and Records              

8.5 Commissioning Records        

8.6 Refrigerant Inventory Record             

8.7 Contingency Provisions         

8.8 The System Register               

8.9 System Log 

8.10 Instruction Manuals             

Section 9 Decommissioning        

9.1  General       

9.2 Recovered Carbon Dioxide  

9.2.1 General    

9.2.2 Carbon dioxide Recovery  

9.2.3 Recovery for recycling to another system 

9.2.4 Recovery for disposal         

Section 10 – References, Standards and Legislation         

APPENDIX A – Definition

APPENDIX B - Maximum Allowable Pressure and Strength Test Procedure           

APPENDIX C - Pneumatic Strength Pressure Test Procedure       

APPENDIX D – Marking and Name Plate Data     

APPENDIX E - Handling Transport and Storage of Refrigerant Cylinders  

APPENDIX F – Commissioning of New Installations          

APPENDIX G – Machinery Rooms and Auxiliary Safety Equipment            

APPENDIX H – Typical Schedule for Inspection and Maintenance              

APPENDIX I - Sample details for Register              

APPENDIX J - Sample Compressor Operating Data and System Log           

APPENDIX K – IOR Policy on Refrigerant Choice 

APPENDIX L – Sealed Freezers